/Engine/Source/Runtime/Engine/Classes/Materials/MaterialInstance.h
Gathers actively used shader maps from all material resources used by this material instance Note - not refcounting the shader maps so the references must not be used after material resources are modified (compilation, loading, etc)
void GetAllShaderMaps ( [TArray](API\Runtime\Core\Containers\TArray)< [FMaterialShaderMap](API\Runtime\Engine\FMaterialShaderMap) * > & OutShaderMaps )